Ugh. Helpppp.

So my periods have been getting progressively later and later. It started about a year ago after I moved out of my parents home to live with my bf. At first I was like a day or two maybe 3 late but nowwww last month I was 16 days late and this month I'm on my 12th day late. I'm not pregnant. I'm just annoyed. Lol and in July I didn't even have a period. This is so frustrating. Is there any logical reason this would happen? Ugh.